DE112013007084B4 - Vehicle approach alarm device - Google Patents

Abstract

A vehicle approach alarm apparatus comprising: a microcomputer (21) having a memory (21a) storing approach alarm sound data to be output, and a signal generator (21b) reading the approach alarm sound data from the memory (21 a) reads out and generates a proximity alarm sound voltage waveform signal indicative of a vehicle approach alarm sound to be output based on the proximity alarm sound data, wherein:the vehicle approach alarm device alarms an approach of a vehicle by outputting the vehicle approach alarm sound from a sound output body (3) according to the approach alarm sound voltage waveform signal output from said microcomputer (21); said microcomputer (21) further comprising:an acquisition device (21c) which acquires a sound output body temperature as a temperature of said sound output body (3 ) acquired; anda sound pressure correcting device (21d) which corrects a voltage level of the approaching alarm sound voltage waveform signal generated by the signal generator (21b) to be larger as the sound output body temperature obtained by the obtaining device (21c) increases; wherein the signal generator (21b) outputs a corrected proximity alarm noise voltage waveform signal to the noise pressure correcting device (21d); andwherein the noise pressure correcting device (21d) corrects the voltage level when a vehicle speed is lower than a predetermined speed.

Description

TECHNICAL AREA

The present disclosure relates to a vehicle approach alarm device for alarming a surrounding area by emitting a sound from a vehicle to which the vehicle is approaching.

BACKGROUND TECHNIQUE

Recently, an electric vehicle (ie, an EV=electric vehicle) and a hybrid vehicle (ie, HV=hybrid vehicle) have a structure for generating a small noise. Accordingly, it is difficult for a pedestrian to find these vehicles close to the pedestrian. In order to increase a degree of recognition of the vehicle located near and around the pedestrian or the like, the vehicle approach alarm device for generating an artificial machine sound is attached to these vehicles (see, for example, JP 2009 - 35 195 A ).

The vehicle approach alarm device outputs an approach alarm sound such as a pseudo moving sound through a speaker. When sound pressure of an output from the speaker is large, noise becomes a problem although warning efficiency increases. On the other hand, when the noise pressure of the output from the speaker is small, although the noise is reduced, the warning efficiency decreases. Accordingly, the noise pressure of the output from the speaker is set at a certain level to satisfy both the noise reduction and the warning efficiency.

However, the vehicle approach alarm device is mounted on the vehicle, so the speaker is affected by ambient temperature around the vehicle. Specifically, the speaker is mounted on an outside of a passenger compartment such as an engine room. The use temperature range in the engine room is very wide (a width of the range is 150°C), such as a range between -40°C and 110°C. Accordingly, the influence on the speaker becomes large. For example, a material of a voice coil in the speaker is copper. A temperature coefficient of resistance of copper is approximately 4,000 ppm/°C. Accordingly, the impedance of the voice coil is changed by about 60% within the temperature range of 150°C. Therefore, the noise pressure of the output from the speaker is shown by the following equation. Accordingly, the noise pressure is reduced as the temperature increases. In the temperature range of 150°C, the noise pressure is easily reduced by 4 dB according to only the temperature change. $$\begin{array}{l}1/\left(\text{speaker}-\text{impedance}\right)\propto \left(\text{speaker current}\right)\propto (\text{Ger}\ddot{\text{a}}\text{ush print the}\\ \text{speaker output})\end{array}$$

In particular, when an attachment position of the speaker is the engine room, since the temperature in the engine room increases greatly after and before running the vehicle, the sound pressure of noise from the speaker is reduced. Accordingly, the warning efficiency is reduced.

The U.S. 2011/0 044 470 A1 describes the solution to the safety problem of electric and hybrid vehicles as follows: If the engine noise of these vehicles is too low so that pedestrians cannot recognize the approaching vehicles, the solution to the problem is that the electric vehicle is equipped with an artificial engine sound generator which is a sounds similar to a petrol engine. This is set up with a CAN module unit that can be connected to the CAN bus communication of the electrical on-board devices. This unit consists of the CAN module and the sound module, which output the sound based on the control signals from the CAN module. The CAN module receives the signals from the driving environment detection device and controls the audio output device (speaker) connected to the sound module and outputs the artificial sound.

From the DE 11 2009 005 469 T5 a device is known which comprises at least one processor and at least one memory containing computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to at least do the following: determine at least one parameter one converters based on information received; and modifying a received signal to operate the transducer based on the determined parameters of the transducer and a frequency spectrum of the received signal.

Further prior art is known from EP 2 760 220 B1, JP 2009 - 101 895 A , U.S. 2012/0 194 328 A1 , WO 2011/ 050 274 A1 and DE 10 2009 005 002 A1 .

SUMMARY OF THE INVENTION

It is an object of the present disclosure to provide a vehicle approach alarm device that limits a change in the sound pressure of the output from the speaker or the like caused by a temperature change and limits the reduction in warning efficiency.

The above object is solved by the subject matter of claim 1. Advantageous developments of the invention are the subject matter of the subsequent dependent claims.

According to an exemplary aspect of the present disclosure, a vehicle proximity alarm device includes: a microcomputer having a memory that stores proximity alarm sound data to be output, and a signal generator that reads the proximity alarm sound data from the memory and a proximity alarm - generates a noise voltage waveform signal indicative of a vehicle approach alarm sound to be output based on the approach alarm sound data. The vehicle approach alarm device alarms an approach of a vehicle by outputting the vehicle approach alarm sound from a sound output body according to the approach alarm sound voltage waveform signal output from the microcomputer. The microcomputer further includes: an acquisition device that acquires a noise output body temperature as a temperature of the noise output body; and a sound pressure correcting device that corrects a voltage level of the approaching alarm sound voltage waveform signal generated by the signal generator to be larger as the sound output body temperature obtained by the obtaining device increases. The signal generator outputs a corrected proximity alarm noise voltage waveform signal to the noise pressure corrector.

In the above vehicle approach alarm device, the voltage level of the approach alarm sound voltage waveform signal is corrected according to the sound output body temperature so that the sound pressure level of the vehicle approach alarm sound actually output from the sound output body is constant. Accordingly, the change in the sound pressure of the output sound from the sound output body with respect to the temperature change is restricted, and the reduction in warning efficiency is restricted. Therefore, both the noise reduction and the warning efficiency are satisfied even if the temperature of the noise output body is changed.

character list

• 1 ist ein Blockschaltbild, welches ein Fahrzeugannäherungs-Alarmsystem zeigt, welches eine Fahrzeugannäherungs-Alarmvorrichtung gemäß einer ersten Ausführungsform aufweist;
• 2 ist ein Diagramm, welches eine Temperaturabhängigkeit eines Widerstands einer Schwingspule in einem Lautsprecher zeigt; und
• 3 ist ein Diagramm, welches eine Beziehung zwischen der Temperatur und einem Geräuschdruckpegel zeigt.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

• 1 12 is a block diagram showing a vehicle approach alarm system including a vehicle approach alarm device according to a first embodiment;
• 2 Fig. 14 is a graph showing a temperature dependency of a resistance of a voice coil in a speaker; and
• 3 Fig. 12 is a graph showing a relationship between temperature and a noise pressure level.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

(First embodiment)

1 12 is a block diagram showing a vehicle approach alarm system including a vehicle approach alarm device according to a present embodiment. Referring to the drawing, the vehicle approach alarm system including the vehicle approach alarm device according to the present embodiment will be explained.

As in 1 As shown, the vehicle approach alarm system includes various sensors 1a, 1b, the vehicle approach alarm device 2, and the speaker 3. As shown in FIG. In the vehicle approach alarm system, the vehicle approach alarm device 2 outputs a pseudo traveling sound from the speaker 3 as a sound generator based on a traveling status detection signal transmitted from various sensors 1a, 1b when the vehicle is moving at a low speed and a low road noise, so that the vehicle approach alarm device 2 alarms a pedestrian or the like around the vehicle to which the vehicle is approaching. Here, the vehicle approach alarm device 2 is separated from the speaker 3 . Alternatively, the vehicle approach alarm device 2 and the speaker 3 may be integrated into one body.

Various sensors 1a, 1b include a vehicle speed sensor 1a and a speaker temperature sensor 1b. The vehicle speed sensor 1a outputs a vehicle speed detection signal of the vehicle, and the speaker temperature sensor 1b is attached to, for example, an outer periphery of the voice coil of the speaker 3 so that the sensor 1b outputs a temperature detection signal indicating the temperature of the speaker 3. The vehicle approach alarm device 2 receives detection signals indicative of vehicle speed and speaker temperature from the vehicle speed sensor 1a and the speaker temperature sensor 1b. According to the vehicle speed and the speaker temperature, the device 2 controls the sound output.

The vehicle approach alarm device 2 comprises a microcomputer 21 , a low pass filter (i.e., LPF) 22 , and a power amplifier (i.e., AMP) 23 .

The microcomputer 21 has a memory as a storage unit 21a and a processing unit. Further, the microcomputer 21 has a signal generator 21b for generating an approach alarm noise voltage waveform signal. The memory stores proximity alarm sound data such as PCM data and a control program for outputting the vehicle proximity alarm sound including a correction calculation program associated with speaker temperature. Using the stored information, the processing unit in the microcomputer 21 determines whether the sound is output based on the vehicle speed indicated in the vehicle speed detection signal, and further reads out the approach alarm sound data at a predetermined reproduction speed. Further, the processing unit outputs the approach alarm sound voltage waveform signal corresponding to the approach sound data from the signal generator 21b.

Specifically, the processing unit in the microcomputer 21 has an acquiring unit 21c for acquiring the vehicle speed and the speaker temperature, and a noise pressure correcting unit 21d for correcting the approaching alarm noise voltage waveform signal to adjust the noise pressure to be constant with respect to the change in the speaker temperature and for controlling the sound output of the vehicle approach alert sound according to the corrected approach alert sound voltage waveform signal.

The acquiring unit 21c receives the temperature detection signal from the speaker temperature sensor 1b and the vehicle speed detection signal from the vehicle speed sensor 1a. Based on these signals, the unit 21c acquires vehicle speed and speaker temperature. The noise pressure correcting unit 21d corrects the voltage level of the approaching alarm noise voltage waveform signal according to the speaker temperature when the vehicle speed acquired by the acquiring unit 21c is lower than a predetermined speed (e.g., 20 km/h). In particular, as will be described later, the unit 21d an amplitude coefficient k of the approach alarm noise voltage waveform signal. The noise pressure correction unit 21d generates a corrected approach alarm noise voltage waveform signal by multiplying the calculated amplitude coefficient k by the approach alarm noise voltage waveform signal, and then outputs the corrected approach alarm noise voltage waveform signal via the signal generator 21b.

Specifically, the temperature correcting unit calculates the amplitude coefficient k corresponding to the speaker temperature acquired by the acquiring unit 21c using the map or the calculation equation stored in the memory. The memory stores the calculation equation or map showing the relationship between the temperature and the noise pressure level in the temperature range, which is assumed to be the temperature change at a place where the speaker 3 is mounted. The speaker temperature is assigned to the calculation equation so that the amplitude coefficient k is calculated. Alternatively, the amplitude coefficient k corresponding to the speaker temperature is selected in the map.

2 Fig. 12 is a graph showing the temperature characteristic of the resistance in the speaker's voice coil. 3 Fig. 12 is a graph showing the relationship between temperature and noise pressure level.

As in 2 As shown, the material of the voice coil in the speaker 3 is copper, for example. The temperature coefficient of resistance of copper is approximately 4,000 ppm/°C. Accordingly, the impedance of the voice coil is changed by about 60% in the temperature range of 150°C.

Accordingly, as indicated by a broken line in 3 is shown, when the voltage level of the approaching alarm sound voltage waveform signal is not changed according to the temperature change, the sound pressure level of the vehicle approach alarm sound actually output from the speaker 3 decreases according to the temperature increase. For example, when the temperature change is in a range of -40°C and 110°C, the noise pressure level is roughly reduced by 4 dB due to only the influence of the temperature change in the range of 150°C. Thus, the temperature correction unit calculates the amplitude coefficient k according to the speaker temperature and corrects the sound pressure level of the output noise of the speaker 3 by multiplying the amplitude coefficient k by the approach alarm noise voltage waveform signal. Therefore, when the vehicle approach alarm sound is output from the speaker 3, the sound pressure level is set to be constant.

Specifically, the voltage level of the approach alarm noise voltage waveform signal is corrected in such a manner that the amplitude coefficient k becomes larger as the speaker temperature increases. For example, in a case where the sound pressure level of the output noise of the speaker 3 is set at room temperature (e.g., around 25°C) as the standard temperature and the sound pressure level is set at the standard temperature in order to satisfy both the noise reduction and the warning efficiency amplitude coefficient k adjusted to satisfy the equation of “k<1”, and the voltage level of the proximity alarm noise voltage waveform signal is reduced when the temperature is lower than the standard temperature; and the amplitude coefficient k is adjusted to satisfy the equation of “k > 1”, and the voltage level of the proximity alarm noise voltage waveform signal is increased when the temperature is higher than the standard temperature. Therefore, although the sound pressure level of the output noise in the speaker 3 has the temperature characteristic shown as the broken line in 3 is shown, the noise pressure level corrected to be constant, shown as the solid line in FIG 3 .

Although the sound pressure level of the output noise is constant in the speaker 3, it is not necessary to be the same fixed sound pressure level. Alternatively, the change in the noise pressure level in the use temperature range is, for example, within a predetermined range (for example, within 2 dB) which has a certain width.

The LPF 22 corresponds to a filter unit. The approach alarm noise-voltage waveform signal output from the signal generator 21b in the microcomputer 21 is fed into the LPF 22 so that a noise component having a high frequency is removed, and the approach alarm noise-voltage waveform signal becomes after the noise component ent is distant, created. For example, the LPF 22 stores a voltage corresponding to the output from the voltage control unit in the capacitor of the LPF 22. Then the voltage is output to the amplifier 23.

The amplifier 23 flows the current in the speaker 3 based on the applied voltage from a constant-voltage power source, which is not shown, the current corresponding to the output of the LPF 22 . The noise pressure of the output noise from the speaker 3 is determined by the magnitude (i.e. amplitude) of the current supplied from the amplifier 23. The magnitude of the current provided by the amplifier 23 is determined by the waveform of the output from the LPF 22 corresponding to the PWM output. Accordingly, the current to be caused to flow through the amplifier 23 is changed according to the approach alarm noise voltage waveform signal whose voltage level (i.e., amplitude) is corrected according to the correction based on the speaker temperature.

As described above, the vehicle approach alarm device according to the present embodiment corrects the voltage level of the approach alarm noise voltage waveform signal according to the speaker temperature so that the sound pressure level of the vehicle approach alarm sound actually output from the speaker 3 is adjusted to be constant be. Accordingly, the change in the noise voltage of the output noise from the speaker 3 in association with the temperature change is restricted. Accordingly, it is possible to restrain the reduction in warning efficiency. Therefore, even if the temperature of the speaker 3 changes, both the noise reduction and the warning efficiency are satisfied.

(Other embodiments)

In the above embodiment, the sound pressure level of the vehicle approach alarm sound actually output from the speaker 3 is fixed or placed in the predetermined range. The sound pressure level of the vehicle approach alarm sound can be controlled in accordance with the vehicle running condition such as the vehicle speed or the acceleration release degree. For example, as the vehicle speed or the acceleration release degree increases, the sound pressure level of the vehicle approach alarm sound is controlled to be larger. Accordingly, the pedestrian recognizes that the approach of the vehicle is quick or the amount of acceleration of the vehicle is large.

In the above case, in general, the vehicle condition and the sound pressure level of the vehicle approach alarm sound have a certain constant relationship. As the speaker temperature changes, the relationship also changes. Therefore, in this case, the amplitude coefficient k of the approach alarm sound voltage waveform signal is calculated based on the speaker temperature, and the approach alarm sound voltage waveform signal is corrected so that the vehicle condition and the sound pressure level of the vehicle approach alarm sound have a certain constant relationship.

Further, in the above embodiment, the approach alarm noise voltage waveform signal itself, which is output from the signal generator 21b installed in the microcomputer 21, is a signal which is already corrected. Alternatively, the voltage level of the approaching alarm noise voltage waveform signal may be corrected by an external device of the microcomputer 21. For example, a voltage control unit is arranged on an outside of the microcomputer 21 . The approach alarm noise voltage waveform signal before being corrected is fed into the voltage control unit, and the microcomputer 21 outputs the control signal corresponding to the amplitude coefficient k. In this case, the voltage control unit corrects the voltage level of the proximity alarm noise voltage waveform signal based on the control signal. Accordingly, effects similar to those in the first embodiment are obtained.

As described in the above embodiment, the vehicle approach alarm device 2 may be separate from the speaker 3 . Alternatively, the speaker 3 may be integrated with the vehicle approach alarm device 2 to form an integrated mechano-electric type device. Here, in the case of the integrated mechano-electric type device, wiring between the speaker 3 and the speaker temperature sensor is short, so that the temperature detection error is reduced, and it is therefore preferable.

In the above embodiment, the speaker 3 is described as an example of the sound output body, and the sound pressure level of the vehicle approach alarm sound actually output from the speaker 3 is set to be constant with respect to the speaker temperature. Alternatively, another sound output body may be used, and a similar treatment may be performed on the sound output body temperature.

The above disclosure has the following aspects.

According to an exemplary aspect of the present disclosure, a vehicle proximity alarm device includes: a microcomputer having a memory that stores proximity alarm sound data to be output, and a signal generator that reads the proximity alarm sound data from the memory and a proximity alarm - generates a noise voltage waveform signal indicative of a vehicle approach alarm sound to be output based on the approach alarm sound data. The vehicle approach alarm device alarms an approach of a vehicle by outputting the vehicle approach alarm sound from a sound output body according to the approach alarm sound voltage waveform signal output from the microcomputer. The microcomputer further includes: an acquisition device that acquires a noise output body temperature as a temperature of the noise output body; and a sound pressure correcting device that corrects a voltage level of the approaching alarm sound voltage waveform signal generated by the signal generator to be larger as the sound output body temperature obtained by the obtaining device increases. The signal generator outputs a corrected proximity alarm noise voltage waveform signal to the noise pressure corrector.

In the above vehicle approach alarm device, the voltage level of the approach alarm sound voltage waveform signal is corrected according to the sound output body temperature so that the sound pressure level of the vehicle approach alarm sound actually output from the sound output body is constant. Accordingly, the change in the sound pressure of the output noise from the output sound body with respect to the temperature change is restricted, and the reduction in the warning efficiency is restricted. Therefore, both the noise reduction and the warning efficiency are satisfied even if the temperature of the noise output body is changed.

Alternatively, the noise pressure correction device may calculate an amplitude coefficient, which becomes larger as the noise output body temperature acquired by the acquisition device increases. The noise pressure correction device calculates the corrected approach alarm noise voltage waveform signal by multiplying the amplitude coefficient by the approach alarm noise voltage waveform signal before correcting it. The noise pressure correction device outputs the corrected proximity alarm noise voltage waveform signal from the signal generator. In this case, the voltage level of the approach alarm noise voltage waveform signal is corrected, and the change in the sound pressure of the output sound from the sound output body with respect to the temperature change is restricted.

Alternatively, the sound pressure correcting device may calculate the amplitude coefficient in order to adjust a sound pressure level of the vehicle approach alarm sound actually output from the sound output body to be constant with respect to a change in sound output body temperature. In this case, "being constant" does not mean that it is necessarily the same fixed sound pressure level. Instead, the noise pressure level may be within a predetermined range having a certain width.

Alternatively, the acquisition device may further acquire a vehicle travel state. The signal generator changes the voltage level of the proximity alarm noise voltage waveform signal based on the vehicle travel state acquired by the acquisition device. The sound pressure correction device calculates the amplitude coefficient of the approach alarm sound voltage waveform signal to adjust a relationship between the vehicle traveling state and the sound pressure level of the vehicle approach alarm sound actually output from the sound output body to be constant with respect to a change in sound output body temperature.

While the present disclosure has been described with reference to embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. The present disclosure is intended to cover various modifications and equivalent arrangements. In addition, besides the various combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.

Claims (4)

Vehicle proximity alarm device comprising: a microcomputer (21) having a memory (21a) storing proximity alarm sound data to be output, and a signal generator (21b) reading out the proximity alarm sound data from the memory (21a) and a proximity alarm sound - generating a voltage waveform signal indicative of a vehicle approach alert sound to be output based on the approach alert sound data, wherein: the vehicle approach alarm device alarms an approach of a vehicle by outputting the vehicle approach alarm sound from a sound output body (3) according to the approach alarm sound voltage waveform signal output from the microcomputer (21); wherein the microcomputer (21) further comprises: an acquisition device (21c) which acquires a noise output body temperature as a temperature of the noise output body (3); and a sound pressure correcting device (21d) which corrects a voltage level of the approaching alarm sound voltage waveform signal generated by the signal generator (21b) to be larger as the sound output body temperature obtained by the obtaining device (21c) increases; wherein the signal generator (21b) outputs a corrected proximity alarm noise voltage waveform signal to the noise pressure correcting device (21d); and wherein the noise pressure correcting device (21d) corrects the voltage level when a vehicle speed is lower than a predetermined speed. Vehicle approach alarm device claim 1 wherein the noise pressure correcting device calculates an amplitude coefficient (k) which becomes larger as the sound body output temperature obtained by the obtaining device increases; the noise pressure correction device calculates the corrected approach alarm noise voltage waveform signal by multiplying the amplitude coefficient (k) by the approach alarm noise voltage waveform signal before it is corrected; and the noise pressure correction device outputs the corrected proximity alarm noise voltage waveform signal from the signal generator. Vehicle approach alarm device claim 2 wherein: the sound pressure correcting device calculates the amplitude coefficient (k) to adjust a sound pressure level of the vehicle approach alarm sound actually output from the sound output body (3) to be constant with respect to a change in sound output body temperature. Vehicle approach alarm device claim 2 wherein: the acquiring device further acquires a vehicle traveling state; the signal generator changes the voltage level of the proximity alarm noise voltage waveform signal based on the vehicle travel state acquired by the acquisition device; and the sound pressure correcting device calculates the amplitude coefficient (k) of the approach alarm sound voltage waveform signal to adjust a relationship between the vehicle traveling state and the sound pressure level of the vehicle approach alarm sound actually output from the sound output body (3) to take into account a change in the noise output body temperature to be constant.

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